1. Field of the Invention
The present invention relates to a light emitting diode (LED) package for displaying multiple colors, and more particularly to the structure of a light emitting diode package, which increases stability in relation to surge and electrostatic discharge (ESD), and improves a degree of freedom in design for miniaturization of the package.
2. Description of the Related Art
Generally, light emitting diodes are widely used in fields of lighting devices and display devices, because of their advantageous features of high brightness, a relatively long lifetime, low consumption of electrical power, and ability to allow miniaturization.
The light emitting diodes can be manufactured as a single package form for use. Such a package is constructed so that a plurality of light emitting diodes are mounted on a single substrate for emitting various different colors according to the user""s requirements, resulting in a multi-color light emitting diode package. The multi-color light emitting diode package mainly takes the form of a three-color light emitting diode package obtained by combining red, green and blue light emitting diodes. Conventionally, the three-color light emitting diode package is configured in such a way that conductive patterns of a printed circuit board are first manufactured, and then three-color light emitting diodes are mounted at parts of the conductive patterns, respectively, for allowing electric power to be applied thereto connected in parallel for multi-color emission.
Among the semiconductor light emitting diodes for use in the three-color light emitting diode package, in particular, green and blue light emitting diodes are very vulnerable to electrostatic discharge and surge. To address such vulnerability, the green and blue light emitting diodes require to be connected to two zener diodes, respectively, in a reverse-polarity manner.
One example of conventional three-color light emitting diode packages is shown in FIG. 1a. FIG. 1a is a plan view illustrating the structure of the conventional three-color light emitting diode package, designated as reference numeral 10, having six terminals.
As shown in FIG. 1a, a substrate 11 of the conventional three-color light emitting diode package 10 comprises first to third anode terminal patterns A1, A2 and A3 formed at one side edge thereof, first to third cathode terminal patterns C1, C2 and C3 formed at the opposite side edge thereof, zener diode mount patterns P1 and P3 extending from the first and third anode terminal patterns A1 and A3, respectively, and a light emitting diode mount pattern P2 extending from the second cathode terminal pattern C2.
The light emitting diode mount pattern P2 is mounted with red, green and blue light emitting diodes 14, 12 and 15. The two zener diode mount patterns P1 and P2 are mounted with zener diodes 16 and 17, respectively. The zener diodes 16 and 17 are connected to the green and blue light emitting diodes 12 and 15, respectively, in a reverse-polarity manner, for addressing the vulnerability of the green and blue light emitting diodes 12 and 15 to electrostatic discharge and surge.
The arrangement structure of such a package also can be expressed as an equivalent circuit diagram as shown in FIG. 1b. As can be seen been from FIGS. 1a and 1b, the conventional three-color light emitting diode package 10 comprises six terminals, but further comprises the two zener diodes 16 and 17 in order to address vulnerability to electrostatic discharge and surge. This increases the number of patterns mounted on the substrate 11, resulting in the increased cross sectional area of the substrate 11.
As stated above, the conventional three-color light emitting diode package has many difficulties in miniaturization thereof because of the addition of zener diodes as well as increase of the pattern""s number. Especially, since the at least two zener diodes to be connected to the green and blue light emitting diodes in a reverse-polarity manner, respectively, have to be additionally mounted on the substrate having a limited cross sectional area, there are many restrictions in the integration of circuit patterns of terminals and the mounted zener diodes.
In order to solve the above problems, and increase a degree of freedom in design as well as achieve miniaturization of a package, of course, omission of the zener diodes may be considered as an option. However, since the green and blue light emitting diodes are very vulnerable to electrostatic discharge and surge as stated above, the omission of the zener diodes may cause the breakdown of the corresponding diodes, resulting in more serious problems including the loss of light emitting function.
Therefore, it has been required to achieve the structure of a new multi-color light emitting diode package, which can achieve miniaturization of the package even while comprising zener diodes for green and blue light emitting diodes, and improve a degree of freedom in design in consideration of various requirements including the cross sectional area of radiation and the like.
Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a multi-color light emitting diode package, which can achieve miniaturization thereof while reducing the number of terminals, by virtue of the application of a newly manufactured zener diode chip having two zener diodes.
It is another object of the present invention to provide a multi-color light emitting diode package, which can widen the range of optimal designs by using a single zener diode chip, thereby improving various performances thereof including radiation, and the like.
In accordance with the present invention, the above and other objects can be accomplished by the provision of a multi-color light emitting diode package mounted thereon with at least three light emitting diodes comprising: a substrate formed at an upper surface thereof with a pattern including three first terminals, and a single second terminal; first and second light emitting diodes among the at least three light emitting diodes, the first and second light emitting diodes being mounted on a conductive mount pattern extending from the second terminal, and all formed at their upper surfaces with first and second electrodes; and a single zener diode chip having two zener diodes, the zener diode chip being mounted on the conductive mount pattern, and formed at a lower surface thereof with a second electrode, and at an upper surface thereof with two first electrodes, wherein the second electrode of the first light emitting diode and one of the first electrodes provided in the single zener diode chip are connected to an associated one of the first terminals, and the second electrode of the second light emitting diode and the other one of the first electrodes provided in the single zener diode chip are connected to another associated one of the first terminals.
Preferably, the first and second light emitting diodes may be green and blue light emitting diodes, respectively.
Preferably, the other remaining light emitting diode among the at least three light emitting diodes may be a red light emitting diode, which is formed at an upper surface thereof with a first electrode, and at a lower surface thereof with a second electrode. In this case, the red light emitting diode may be mounted on the substrate so that it is positioned on a conductive mount pattern extending from the other remaining first terminal among the three first terminals, which is not connected with the first electrodes of the single zener diode chip, and the second electrode of the red light emitting diode may be connected to the second terminal or the mount pattern extending from the second terminal.
Alternatively, the other remaining light emitting diode among the at least three light emitting diodes may a red light emitting diode, which is formed at an upper surface thereof with a second electrode, and at a lower surface thereof with a first electrode. In this case, the red light emitting diode may be mounted on the substrate so that it is positioned on the conductive mount pattern extending from the second terminal, and the second electrode of the red light emitting diode may be connected to the other remaining first terminal among the three first terminals, which is not connected with the first electrodes of the single zener diode chip.
Preferably, the single zener diode chip employed in the present invention may comprise a first conductive substrate formed at a lower surface thereof with the second electrode, and two second conductive impurity areas defined at an upper portion of the first conductive substrate while being spaced apart from each other, each second conductive impurity area being formed at an upper surface thereof with one of the first electrodes.
As stated above, according to the present invention, it is possible to provide various optimal design solutions using the single zener diode chip.
According to the various optimal design solutions, preferably, the mount pattern extending from the second terminal may be positioned at a central region of the substrate, and the first terminals and the second terminal may be positioned at both side edges of the substrate.
Preferably, the red, blue and green light emitting diodes may be arranged in a triangular pattern. In this case, the single zener diode chip may be preferably positioned adjacent to the blue and green light emitting diodes of the triangular pattern.
Referring to the detail arrangement structure of the multi-color light emitting diode package according to the present invention, preferably, the two first terminals connected to the two first electrodes of the single zener diode chip, respectively, may be positioned at both side edges of the substrate adjacent to the blue and green light emitting diodes, respectively, and the other remaining first terminal and the second terminal may be positioned at both side edges of the substrate adjacent to the red light emitting diode, respectively.
Preferably, the first terminals may be cathode terminals, and the second terminal may be an anode terminal.